The Charger, Champ, and Cruiser are two piece chassis assemblies. There are 4 holes in the chassis main section, and 4 holes in the front axle carrier. By lining these up differently, you can get several wheelbases out of these chassis. The 3″, 3.25″, and 3.5″ are the easiest. You still have 4 screws holding the chassis together and plenty of clearance. If you go out to 3.75″, you will have very little material overlap and only 2 screws. We recommend using our long nose pieces for wheelbases over 3.5″. If you set the nose in as far as possible, you can get a 2.75″ wheelbase. There will be very little room for the front tires though. You may have to grind the chassis side pan.